1. Field
Example embodiments relate to a semiconductor device using magnetic domain wall movement.
2. Description of the Related Art
A flash memory is a non-volatile memory that has been widely used in various applications. The flash memory, however, has relatively low operating speed and a relatively short lifetime. To overcome such problems, new types of memory have been introduced, e.g., a magnetic random access memory (MRAM), a ferroelectric random access memory (FRAM), a phase-change random access memory (PRAM), and a resistive random access memory (RRAM). However, because these new memories include switching elements connected to respective memory cells, increasing a degree of integration may be difficult.
Thus, an information storage device using magnetic domain wall movement has been introduced. This information storage device may be a non-volatile information storage device in which a switching element is not required to be connected to a memory cell.
A minute magnetic region that constitutes a magnetic body may be referred to as a magnetic domain. The direction of magnetic moments in a magnetic domain may be identical. A magnetic domain wall may be a boundary portion between magnetic domains having different magnetization directions. The magnetic domains and the magnetic domain walls may be moved within a magnetic body by supplying current to the magnetic body. By using the principle of movement of magnetic domains and the magnetic domain walls, embodying a non-volatile information storage device that does not need a switching element for controlling access to a memory cell may be possible.
However, semiconductor devices using magnetic domain wall movement may be still at an early stage of development, and several problems need to be overcome so that they may be put to practical use. For example, continuously supplying a pulse current with a density of about 109 to about 1012 A/m2 may be supplied to a magnetic body in order to move magnetic domains and magnetic domain walls, but the magnetic body becomes heated due to the pulse current, thereby causing various problems. If the magnetic body becomes heated, the retention of information recorded on the magnetic domains thereof may be degraded and the shape of the magnetic body may deform.
Also, as the temperature of the magnetic body is increased, the electrical resistance of the magnetic body may also be increased, and thus, an increased voltage should be applied to the magnetic body in order to supply the same amount of current. Furthermore, the moving speed of the magnetic domain walls and the threshold density of current necessary to movement of the magnetic domain walls vary according to the temperature of the magnetic body. Accordingly, controlling an information storage device using magnetic domain wall movement and securing the reliability thereof may be difficult.